Catheter for applying medication into the endolymphatic sacs of the cochlea

ABSTRACT

A catheter for administering medication into the endolymphatic sacs of the cochlea of the inner ear in humans, through at least one membrane of the inner ear. The catheter is designed with at least one outflow aperture at one end for the medication being administered and with an anchoring element. A medication dosage system can be connected to the other end of the catheter. The outflow aperture can be fed through the membrane of the inner ear and the anchoring element is designed so that it can anchor itself against this membrane.

BACKGROUND OF THE INVENTION

[0001] The invention concerns a catheter for administering medicationinto the endolymphatic sacs of the inner ear in humans, through at leastone membrane of the inner ear. The catheter has at least one outflowaperture at one end for the medication being administered. There is ananchoring element for the catheter at this end to anchor the catheter tothe membrane. There is also a medication dosage system connected to theother end of the catheter.

THE PRIOR ART

[0002] This kind of catheter is used to administer medication into theendolymphatic sacs of the inner ear. Administration of medication to theinner ear is sometimes necessary to combat ear diseases and for balance.In particular, it is used for treating symptoms such as loss of hearing,vertigo or ringing in the ears (tinnitus). Tinnitus is described as theawareness of sound, such as ringing or whistling, within the inner earwithout there actually being any external sound source.

[0003] The reasons for the emergence of these noises, only audible tothe patient, are numerous, and the pathogenesis of such has not beenclearly explained to date. Due to the difficulty in accessing the innerear to treat the respective illnesses, the administration of medicationhas been standard. It has not been possible to effectively treatdiseases of the inner ear, or treatment has only been performed withdifficulty, due to the side effects of medication. Nowadays, treatmentfor hearing loss in the inner ear, vertigo or tinnitus is performed byvasoactive infusions, steroids or hyperbaric oxygen therapy.Anaesthetics and antidepressants are also used along with physical,surgical and psychotherapeutic measures.

[0004] Systemically administered medication not only affects the area ofthe inner ear but also the whole body. Side effects thereby occur evenwith minimal dosage, which makes specific therapy of the disorder of theinner ear impossible. The result of this is that the majority ofpatients today cannot be effectively treated. Physical,psychotherapeutic and surgical measures can only help in a very smallpercentage of cases.

[0005] Meaningful and effective therapy to the inner ear can only beachieved with a localized dose of drugs or by electrically inducedstimuli. However, specific application of drugs has always posedproblems.

[0006] In one known procedure, medication is administered via a tympanictube in the middle ear with subsequent uncontrolled diffusion into theinner ear via the round window membrane. With this type of knownprocedure, the only medication that can be applied is that which is alsodiffusible, which is not the case with some types of medication. Inaddition, it is virtually impossible to determine, predict and monitorthe diffusion rate of diffusible substances. Therefore, the amount ofmedication selected must err on the high side, so that an adequateamount of the applied substance per diffusion can reach the inner ear.

[0007] A generically known catheter, such as that produced byNeuro-Biometrix USA (now called Intra Ear) distributed under its tradingname “Round Window μ Cath” and “Round Window E Cath”, has a somewhatspherical flexible end portion, which is clamped into the niche of themembrane of the round window and anchors itself there. This ending hasseveral apertures, from which the medication can be discharged anddiffuses right through the membrane of the round window. These outflowapertures are spaced at a distance from the membrane of the roundwindow. However this known catheter can only apply diffusiblemedication, as these substances must be able to diffuse right throughthe membrane of the round window.

[0008] It would be desirable to have a controllable directadministration of medication into the lymph filled compartments of thecochlea, as only then is specific therapy of the symptoms of the diseasepossible. Since the lymphatic fluid in the cochlea directly bathes thesensory cells requiring therapy, as a blood supply for the sensory cellsis not however immediately available, it is therefore not possible toadminister medication via the bloodstream directly to the location ofthe damaged cells. Therefore, the ability to control the directadministration of medication into the inner ear fluids is desired. Untilnow, only the following substances and methods have been available:steroids and osmotically effective substances, tinnitus suppressantmedications from the group of membrane-effective drugs and transmittersubstances, neurotrophine (i.e., substances that facilitate regenerationor protection of damaged inner ear auditory cells and attacked auralnerve tissues), antioxidants, gene therapy, the application ofelectrically charged particles for the treatment of tinnitus andototoxic medication for eliminating equilibrium sensitive cells.

SUMMARY OF THE INVENTION

[0009] It is therefore an object of this invention to design a catheterof the kind mentioned previously, so that it facilitates directapplication of medication into the inner ear, and which also offers safeand secure anchoring in the inner ear.

[0010] It is another object of the invention to provide a catheter thatwill not negatively affect the auditory performance of the patient andwhich can be removed again without any problems, once therapy iscomplete.

[0011] These and other objects are achieved by way of a catheteraccording to the invention having at least one outflow aperture at oneend for the medication being administered and with an anchoring element.A medication dosage system can be connected to the other end of thecatheter. The outflow aperture can be fed through the membrane of theinner ear, and the anchoring element is designed so that it can anchoritself against this membrane.

[0012] The invention envisages a catheter of the type mentioned above,designed so that the outflow aperture can be fed through the tympanicmembrane and the anchoring element anchors itself directly against themembrane.

[0013] A catheter of this kind can be created in a surprisingly simplemanner to facilitate the direct application of medication into the innerear and provide safe and durable anchoring within the inner ear. Thecatheter is designed so that it can be affixed to the round windowmembrane, to the base of the stapes at the oval window, or to themembrane of the endolymphatic sac, and the medication is then fed intothe compartment behind the membrane.

[0014] The catheter according to the invention can also be combined witha medication dosage system, particularly one for micro-dosage system.

[0015] Depending upon whether the catheter according to the invention isto be anchored at the round window membrane, to the base of the stapesat the oval window, to the membrane of the endolymphatic sac or to thebone between the scala tympani and the cochlea duct, a posteriortympanotomy (starting at the drilled tympanic membrane) is well suitedas the access route to these membranes for access to the round and ovalwindows, and the transmeatal access route (via the auditory canal) isalso suitable for positioning the catheter according to the invention. Acombined access route can offer additional advantages where appropriate.The catheter for the endolymphatic sac can be anchored within theparameters of a mastoidectomy (starting at the drilled tympanicmembrane) and then exposing the sac in the area of the sigmoid sinus. Adiagonal incision in the area of the upper and lateral sections is made.The catheter (depending on the size of the system) is fed into theopening and anchors itself.

[0016] The configuration of the elements facilitates adequate sealing ofthe exposed cochlear duct. The connective tissue membrane offersadditional security. Due to the flexible nature of the suspendingcatheter at the respective membrane, deterioration of auditoryperformance is not expected. Removal of the catheter can be performedwithout damage, and closure of the lumens can be achieved withconnective tissue or similar tissue. A measuring instrument or otherinstruments make the selection of size, positioning, and fixing of thecatheter very simple. It is possible to integrate a wide variety ofsensors and electrodes into the catheter. It is also possible to designthe catheter extremity with various coupling elements to facilitate theattachment of a micro-dosage system.

[0017] Another advantage of the catheter according to the presentinvention is that it can be easily removed upon completion of therapy.Upon removal of the catheter, the aperture left behind in thecorresponding membrane can be covered and closed up initially withgrafted tissue, so that fluid cannot flow through the opening out of theinner ear. Subsequently, the scar tissue heals as a natural process,whereupon the aperture completely closes up. This scar tissue does notaffect auditory performance.

[0018] In a preferred embodiment of the invention, one end is designedwith a disc arranged across and encompassing the catheter tube foranchoring it to the round window membrane (or for anchoring it to thebasilar membrane) and having a cannula point with an outflow aperture,which can be fed through the membrane. The disc has at least oneanchoring element on its edge, which is designed to anchor against theosseous border of the round window (or the basilar membrane). Thecannula point can be combined with an electro-conductive cable and maybe made of a metallic material. The disc can have a diameter of between0.7 mm and 1.2 mm.

[0019] This catheter can take advantage of the anatomical geometry ofthe round window and its membrane in a surprisingly simple way. Thenwith the cannula point, disc and anchoring stays, it is only necessaryto pierce through the membrane of the round window with the cannulapoint, after which the anchoring stay or stays snap into the osseousborder of the round window. This is because this osseous border of theround window already has overhanging edges that are well suited forpositioning the anchoring elements.

[0020] In another embodiment of the invention, one end of the catheterhas a bulbous extension, the end wall of which has an outflow apertureand at least two anchoring stays made of a flexible material havingmemory and arranged concentrically around the outflow aperture. Theanchoring stays can be fed through the footplate of the stapes at theoval window and anchor themselves against the inner surface of thefootplate. In further embodiments of this configuration, the bulbousextension is fitted with a clip, which anchors itself against the baseof stapes. Another configuration has the catheter, the bulbousextension, and the stays enveloped in a removable tube, which has aninternal diameter corresponding to the outer diameter of the bulbousextension.

[0021] This embodiment of the catheter is very suitable for attachmentto the footplate of the stapes at the oval window. Also, attachment ofthe catheter to the footplate is performed in a conceivably simplemanner. First, an aperture is made in the footplate of the oval window.Then, the catheter with its bulbous extension is anchored at thefootplate of the oval window so that the anchoring elements are fedthrough the aperture in the footplate.

[0022] Due to the memory characteristics of the material of theanchoring stays, they flex themselves outwards after they have beeninserted, by way of which the catheter is thereby anchored. The optionalenveloping tube extends the anchoring stays in an axial direction andanchors the bulbous extension to the footplate of the oval window usinganchoring stays, and the anchoring stays are fed through the opening inthe footplate. As soon as the anchoring stays have been fed through thefootplate and have left the rigid mantle of the enveloping tube, theanchoring stays flex according to the memory characteristic of thematerial and anchor themselves against the inner surface of thefootplate. Subsequently, the enveloping tube can be pulled out towardsthe rear and removed. It is possible to remove the catheter by pullingit, because the metal has the property of memory and has a flectionalresistance lower than the tensile resistance of the footplate.

[0023] In a third embodiment of the invention, one end of the catheteris fitted with a conical body having a front outflow aperture, whoseminimum diameter is greater than the diameter of the catheter tube. Thebody is fitted with at least two hook-like anchoring elements bentbackwards to its outer mantle, which together with a front sub-sectionof the conical body can be fed through the membrane of the endolymphaticsac, and anchor themselves against the inner surface of the membrane ofthe endolymphatic sac.

[0024] It is also easy to feed this kind of catheter through themembrane of the endolymphatic sac and to anchor it against the membraneof the endolymphatic sac.

[0025] In accordance with practical embodiments of the invention, thecoupling elements of the catheter are made of carbon material ortitanium oxide ceramic. The other parts of the catheter can be made ofsilicon. These materials have proven to be particularly suitable forimplantation into the human body without affecting the surroundingtissue.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other objects and features of the present invention will becomeapparent from the following detailed description considered inconnection with the accompanying drawings. It is to be understood,however, that the drawings are designed as an illustration only and notas a definition of the limits of the invention.

[0027] In the drawings, wherein similar reference characters denotesimilar elements throughout the several views:

[0028]FIG. 1 shows a side view of a first embodiment of a catheteraccording to the invention;

[0029]FIG. 2 shows a perspective view of a second embodiment of thecatheter according to the invention;

[0030]FIGS. 3 and 4 show a side view of a detail of the catheter shownin FIG. 2;

[0031]FIG. 5 shows a schematic view of a third embodiment of thecatheter according to the invention;

[0032]FIG. 6 shows an enlarged perspective of the anatomical features ofthe human inner ear; and

[0033]FIG. 7 shows a schematic view of a micro-dosage system used inconjunction with the catheter shown in FIGS. 2 to 4, in position in thehuman ear.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Referring now in detail to the drawings, the geometry of thehuman inner ear 1 is explained, using FIG. 6 as an example. Ear 1comprises the utricle 2, the ampulla of the lateral semicircular canal3, the saccule 4, the cochlear duct 5 and the endolymphatic sac 6. Theinner ear 1 is particularly demarcated by the footplate 7 of the stapesat the oval window 8, by the membrane 9 of the round window 10 and bythe membrane 11 of the endolymphatic sac 6. An additional access routeto the inner ear is provided by the auditory tube 12.

[0035] For physiological reasons, the footplate 7 of the oval window 8,the membrane 9 of the round window 10 as well as the membrane 11 of theendolymphatic sac 6 are suitable for applying medication to the innerear 1. Also suitable is the basilar membrane which is not depicted inFIG. 6, if an operation similar to the Cochlear Implant Operation isgoing to be performed.

[0036]FIG. 1 depicts a first embodiment of a catheter 20 according tothe invention. Catheter 20 is fitted with a catheter tube 22, only asection of which is depicted in FIG. 1. At the one end 24, the catheter20 is fitted with an outflow aperture 26. It is through this outflowaperture 26 that the medication fed through the catheter tube 26 canleave the catheter 20 and discharge into the inner ear 1.

[0037] At the end 24 of catheter 20, an anchoring element 28 is arrangedfor anchoring catheter 20 to membrane 9 of round window 10. Anchoringelement 28 comprises a disc 30, which is arranged across andencompassing catheter tube 22 and which is in contact with membrane 9.Disc 30 is designed with two anchoring stays 34, 36 on its edge, whichanchor themselves against overhanging osseous border 37 of round window10.

[0038] The one end 24 with outflow aperture 26 has a cannula point 38.Cannula point 38 can be made of metallic material, for example V4A steelor titanium, and is connected to an electro-conductive cable 40 asindicated in FIG. 1. Cable 40 can be used for applying electricallyinduced stimulations to inner ear 1, or for recovering electricresponses from the inner ear.

[0039] Disc 30 can be made of silicon and can have a diameter of 0.7,1.2, or 1.7 mm with a thickness of 0.2 mm. Cannula point 38 preferablyhas a diameter of 0.3 mm and a length of 0.5 mm. Catheter tube 22 has aninternal diameter of 0.3 mm, an outer diameter of 0.7 mm and a length ofup to approximately 200 mm, and can be connected to a dosage system 96still to be described. Anchoring stays 34, 36 at edge 32 of disc 30 canbe between 0.7 and 1.0 mm long.

[0040] Catheter 20 depicted in FIG. 1 can be attached at a cochleostomy,i.e., at an artificially created aperture in the inner ear. Here thebone of the spiral organ/cochlea is removed using a drill and the innerbone membrane, the so called scala timpani, is exposed across a largeenough surface, about 2×2 mm in size. The scala timpani is a connectivetissue membrane, which surrounds the perilymph as the innermost layer.After exposure, similar to the membrane 9 of round window 10, it can bepunctured and disc 30 with anchoring elements 34, 36 can be anchored atthe surrounding osseous border.

[0041] Disc 30 also prevents cannula point 38 from penetrating too farinto inner ear 1 and in so doing guarantees a maximum depth ofinsertion. At the same time, disc 30 acts as a sealing element at theinner ear 1 side. The maximum guaranteed depth of penetration preventsdamage to the basilar membrane or to other intracochlear structures. Dueto the minimal depth of insertion, development of foreign body reactionsand/or direct mechanical damage can be avoided or at least considerablyreduced.

[0042] In FIGS. 2-4, the second embodiment of catheter 50 is depictedaccording to the invention. This catheter 50 has a bulbous extension 52,which is arranged at the end 54 of the catheter 50. Catheter 50 also hasa catheter tube 56, only a section of which is shown in FIGS. 2-4.

[0043] One outflow aperture 58 is arranged centrally at the one endsurface 56 of the bulbous extension 52, through which medication appliedinto catheter 50 can be discharged. Several anchoring elements 60 in theform of anchoring stays 62 made of a material having memory are arrangedconcentrically around the outflow aperture 58 of bulbous extension 56.These stays are designed so that after being extended they spring backinto their original position, as shown in FIG. 4.

[0044] In order to be able to anchor catheter 50 into position atfootplate 7 of oval window 8 as shown in FIG. 2, footplate 7 is pierced,then anchoring stays 62 are fed through this aperture in footplate 7,after which they anchor themselves against the inside of the footplate7. In order to ease insertion of front end 54 of catheter 50, anenveloping tube 64 can be used, which is indicated in FIGS. 3 and 4. Asshown in FIG. 3 the enveloping tube 64 covers the bulbous extension 52and the anchoring stays 62, so that they can be extended axiallyforward.

[0045] If catheter 50 is placed at the opening of footplate 7 in thisway, then catheter 50 can be pushed forward toward the inner ear. Assoon as anchoring stays 62 have passed through the opening at footplate7 and emerge away from the area influenced by the enveloping tube 64,they spring back due to their memory and anchor themselves at the insideof footplate 7. After that, enveloping tube 64 can be removed by pullingit out backwards.

[0046] Bulbous extension 52 can be made of silicon or from a relatedmaterial and has a diameter of 1 mm and a thickness of 0.6 mm. The innerlumen of bulbous extension 52 can correspond to the inner lumen ofcatheter tube 52, i.e., approximately 0.4 mm.

[0047] Similar to catheter 20 in FIG. 1, catheter 50 can be fitted witha cable 66, which ends directly at the end surface 56 of bulbousextension 52, or it can be connected to an anchoring element 62, if thisis made of metallic material.

[0048] As shown in FIG. 2, bulbous extension 52 is fitted with a clip68, which can be made of platinum for example, and which anchors itselfat end 70 against one of the crura of the base of the stapes 14.

[0049] A third embodiment of a catheter 80 according to the invention isschematically depicted in FIG. 5. Catheter 80 is fed into theendolymphatic sac 6 through membrane 11 of endolymphatic sac 6. Catheter80 has a catheter tube 82, of which only a section is depicted in FIG.5, as well as an end 84 with outflow aperture 86. Catheter 80 is alsofitted with an anchoring element 88. Catheter 80 is designed with end 84as a conical body 90, which has a minimum diameter greater than thediameter of catheter tube 82.

[0050] Hook-like anchoring stays 94 acting as anchoring elements 88 areattached to the mantle surface 92. These hooks are flexed with theirends toward the inner surface of membrane 11, so that after insertioninto the aperture in the membrane 11, conical body 90 can be pushedthrough with hook-like anchoring elements 94 at least part way throughthe aperture in the membrane 11. This prevents conical body 90 fromslipping out from the aperture in membrane 11 by hook-like anchoringelements 94. Anchoring elements 94 are made of silicon like body 90. Inthe embodiment shown, they have a length of 0.3 mm and a diameter of 0.1mm.

[0051]FIG. 7 schematically depicts the human ear 16 with the eardrum 18,which is fitted with a catheter 50 as shown in FIGS. 2-4. A cathetertube 52 is connected to a micro-dosage system 96, which can be implantedinto the bony tissue 17 of ear 16. Catheter tube 52 passes through themiddle ear. Catheter 50 is connected to the oval window 8 as shown inFIGS. 2-4.

[0052] The micro-dosage system 96 can have a drug reservoir, amicro-pump and an IC control, none of which are depicted. This releasesa programmed amount of medication via catheter tube 52 into the innerear 1. Micro-dosage system 96 also has a tube 98 emerging at the bodyouter mantle, through which medication can be supplied to themicro-dosage system 96. It is also possible for the medication to betranscutaneously fed into micro-dosage system 96 via a syringe.

[0053] Accordingly, while only a few embodiments of the presentinvention have been shown and described, it is obvious that many changesand modifications may be made thereunto without departing from thespirit and scope of the invention.

What is claimed is:
 1. A catheter for administering medication into theendolymphatic sacs of the inner ear in humans through at least onemembrane of the inner ear, the membranes comprising the membrane of theround window, the membrane of the endolymphatic sac and the basilarmembrane, and the inner ear further having a stapes footplate, and ascala tympani with an osseous border, comprising: a catheter tube havingtwo ends; at least one outflow aperture at one end of the catheter tubefor administration of the medication through one of the membranes of theinner ear; an anchoring element at said one end for anchoring thecatheter directly against the membrane; and a medication dosage systemconnected to the other end of the catheter.
 2. A catheter according toclaim 1, wherein the anchoring element comprises a disc arranged acrossand encompassing said catheter tube for anchoring said catheter tube,said disc covering the round window of the inner ear and having at leastone anchoring stay on an edge, said stay anchoring against an osseousborder of the round window, and further comprising a cannula point atsaid outflow aperture, said cannula point being feedable through saidmembrane.
 3. A catheter according to claim 1, wherein the anchoringelement comprises a disc arranged across and encompassing said cathetertube for anchoring said catheter tube to the basilar membrane, said dischaving at least one anchoring stay at an edge, said stay anchoringagainst the osseous border of the scala tympani, and further comprisinga cannula point at said outflow aperture, said cannula point beingfeedable through the scala tympani.
 4. A catheter according to claims 2,wherein said cannula point is connected to an electro-conductive cable.5. A catheter according to claim 2, wherein said disc has a diameter of0.7 mm to 1.2 mm.
 6. A catheter according to claim 1, wherein saidcannula point is made of a metallic material.
 7. A catheter according toclaim 1, wherein said one end has a bulbous extension with an endsurface containing said outflow aperture, said bulbous extension havingan outer diameter and being designed with at least two concentricanchoring stays encompassing said outflow aperture, said stays beingmade of a flexible material with memory, wherein said anchoring staysare fed through the footplate of the stapes of the oval window and whichanchor themselves against the inner surface of the joint.
 8. A catheteraccording to claim 7, wherein said bulbous extension is fitted with aclip, said clip anchoring itself against the stapes footplate.
 9. Acatheter according to claim 7, wherein said bulbous extension and saidanchoring stays are enveloped in a removable tube having an innerdiameter corresponding to the outer diameter of said bulbous extension.10. A catheter according to claim 1, wherein said anchoring elementcomprises a conical body with a front outflow aperture whose minimumdiameter is greater than the diameter of the catheter tube, said conicalbody having at least two hook-like anchoring elements bent backwards atan outer mantle, wherein said hook-like anchoring elements together witha front sub-section of the conical body are fed through said membraneencompassing the endolymphatic sac, and anchor themselves against aninner surface of said membrane of the endolymphatic sac.
 11. A catheteraccording to claim 10, wherein said catheter is made of a carbonmaterial.
 12. A catheter according to claim 10, wherein said catheter ismade of titanium dioxide ceramic.